The inventors herein have recognized a need for an improved system for controlling operation of a contactor. The system provides a technical effect of utilizing diagnostic diversity for opening a contactor. In particular, the system stops outputting a control signal to open the contactor, and then measures a low side sense signal from a low side sense circuit electrically coupled to a low side end of a contactor coil, or a high side sense signal from a high side sense circuit that is electrically coupled to a high side end of the contactor coil, to determine whether the contactor has a closed operational position, and if not, the system stops outputting another control signal to open the contactor.